[PATCH 1/2 v2] gpio: omap: make gpio numbering deterministical by using of aliases

[Grygorii Strashko]

On 06/14/2016 09:57 PM, Uwe Kleine-König wrote:
> Traditionally the n-th gpio device probed by the omap gpio driver got
> the gpio number range [n*32 .. n*32+31].
> When order of the devices probed by the driver changes (which can happen
> already now when some devices have a pinctrl and so the first probe
> attempt returns -ENODEV) the numbering changes.
>
> To ensure a deterministical numbering use of_alias_get_id to determine
> the base for a given device. If no respective alias exists fall back to
> the traditional numbering.
>
> For the unusual case where only a part of the gpio devices have a
> matching alias some of them might fail to probe. But if none of them has
> an alias or all, there is no conflict which should be good enough to
> maintain backward compatibility.
>
> Signed-off-by: Uwe Kleine-König <u.kleine-koenig at pengutronix.de>
> ---
>   drivers/gpio/gpio-omap.c | 19 ++++++++++++++++++-
>   1 file changed, 18 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpio/gpio-omap.c b/drivers/gpio/gpio-omap.c
> index b98ede78c9d8..4d91792e7266 100644
> --- a/drivers/gpio/gpio-omap.c
> +++ b/drivers/gpio/gpio-omap.c
> @@ -1053,9 +1053,26 @@ static int omap_gpio_chip_init(struct gpio_bank *bank, struct irq_chip *irqc)
>   			bank->chip.parent = &omap_mpuio_device.dev;
>   		bank->chip.base = OMAP_MPUIO(0);
>   	} else {
> +		int gpio_alias_id __maybe_unused;
> +
>   		bank->chip.label = "gpio";
> -		bank->chip.base = gpio;
> +
> +#if defined(CONFIG_OF_GPIO)
> +		/*
> +		 * Traditionally the base is given out in first-come-first-serve
> +		 * order.  This might shuffle the numbering of gpios if the
> +		 * probe order changes.  So make the base deterministical if the
> +		 * device tree specifies alias ids.
> +		 */
> +		gpio_alias_id = of_alias_get_id(bank->chip.of_node, "gpio");
> +		if (gpio_alias_id >= 0)
> +			bank->chip.base = bank->width * gpio_alias_id;
> +		else
> +#endif
> +			bank->chip.base = gpio;
>   	}
> +
> +
>   	bank->chip.ngpio = bank->width;
>
>   	ret = gpiochip_add_data(&bank->chip, bank);
>

Reviewed-by: Grygorii Strashko <grygorii.strashko at ti.com>

-- 
regards,
-grygorii